12 May Organic Molecular Structures | Questions and Answers

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12. Several compounds are shown below. Refer to them to answer the questions that follow.

a) Terephthoyl chloride and ethylene glycol react by polymerisation to produce a polymer called poly(ethylene terephthalate), commonly known as PET. PET is used to make soft drink bottles. Fumes of an acidic gas are also produced.
(i) Suggest whether PET is formed by addition or condensation polymerisation and explain your choice by comparing the two types of polymerisation.
(ii) Draw the full structural formula of PET.
(iii) Suggest one physical property of PET that makes it suitable as a soft-drink bottle.
b) Oxalic acid is a dicarboxylic acid. Its structure is shown above.
(i) State the type of reaction that converts ethylene glycol to oxalic acid.
(ii) Draw the structural formula of the product formed when oxalic acid undergoes esterification with phenol, which has the structural formula shown above. The ester produced, called diphenyl oxalate, is used to manufacture glowsticks.

c) Perspex is used as a glass substitute for making airplane windows. Its chemical name is poly(methyl 2-methyl propenoate).
(i) Name the functional group present in Perspex.
(ii) Give the name of the monomer of Perspex and draw the full structural formula of this monomer.
(iii) If 500 g of the monomer of Perspex is used and the polymerisation goes to completion, determine the average mass of Perspex produced.

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12.a.i. Condensation
In addition polymerisation, identical monomers react to produce only 1 product, the polymer. In condensation polymerization, small molecules are lost, and in this reaction, these molecules are those of the acidic gas.
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iii. Strong, impact-resistant, lightweight, resistant to corrosion